The Muscular System Functions & Anatomy

Functions of the Muscular System

Movement Movement of bones Actions of muscles Work like rubber bands Depends on attachment points on the bones

Posture Maintain body position Tonic Contraction Produces no movement Maintain muscle tone

Heat Production Contraction produces heat required to maintain normal body temp.

Types of Muscle Tissue Skeletal Smooth Cardiac

Skeletal Muscle Striated Voluntary “Red Meat” Attached to bones Perform contractions that lead to movement of bones Joints                            

Smooth Muscle Non-striated (smooth) Involuntary Found in hollow walls of organs Intestine Blood vessels Etc. Movement of materials through tubes

Cardiac Muscle Striated – intercalated discs Involuntary Heart Contraction

Structure of Skeletal Muscle Organs = muscles Extend from bone to bone Attached by tendons Origin – fixed point Insertion – moves during contraction

Microscopic Structure Contractile fibers grouped in bundles Contain Proteins (filaments) Actin Myosin Filaments slide toward each other during contraction

Stimulus Muscle contracts when stimulus reaches certain intensity All on none Motor Unit Nerve + Muscle Neurotransmitter crosses gap between

Muscular System Actions

Actions are based on…. Origin Insertion Insertions move toward origins Fixed point of muscle attachment Insertion Moveable point of muscle attachment Insertions move toward origins Direction of muscle fibers

Actions Flexion (lateral*) Extension Hyperextension Decreasing the joint angle Extension Increasing the joint angle Hyperextension

Actions… Abduction (Hz*) Adduction (Hz*) Circumduction Moving away from body Adduction (Hz*) Moving toward body Circumduction Cone-like movement

Actions… External Rotation Internal Rotation L/R Rotation lateral Medial L/R Rotation

Actions… Plantar Flexion Dorsi Flexion Inversion Eversion Pointing toes Dorsi Flexion Bringing toes toward shins Inversion Soles sweep toward each other Eversion Soles sweep away

Actions… Pronation Supination Opposition Reposition Palms downward Palms upward Opposition Thumb moves across palm Reposition Thumb returns

Actions… Depression Elevation Protraction Retraction Lowering shoulders Elevation Shoulders shrug upward Protraction Jutting forward Retraction Jutting back